Feeding and ecomorphology of seven flatfish species in the North-North-West Aegean Sea, Greece

Abstract

The diet composition and possible relationships between mouth area and intestine length with feeding were investigated for seven flatfish species in the North-North-West Aegean Sea. Samples were obtained from commercial fisheries (trawls and gillnets) on a seasonal basis, and a total of 444 individuals was analysed. The two most abundant species, Arnoglossus laterna and Citharus linguatula, preyed mainly on fish, and there were no differences in the feeding habits of the two species with season or sex. The remaining five species fed on small benthic invertebrates, mainly Crustacea and Polychaeta. Multivariate analysis showed that, based on their diet, the seven species formed three distinct groups. The mean mouth area and relative gut length differed significantly between the three groups, indicating differences in some of the morphological characteristics in order to avoid trophic overlap. The estimated trophic levels of these species (from 21 literature sources) ranged from 3.00 for Symphurus nigrescens to 4.49 for A. laterna and C. linguatula, indicating that flatfish span all trophic levels above 3.